Analyzer channel for use in an automatic hysteresis loop recorder



E. R. czERLlNsKY ET AL 2,968,004 ANALYZER CHANNEL FOR USE IN AN AUTOMATIC HYSTERESIS LOOP RECORDER original Filed sept. 27, 195e Jan. 10, 1.961

5 Sheets-Sheet 1 Jan. 10, 1961 E. R. CZERLINSKY ET AL ANALYZER CHANNEL FOR USE IN AN AUTOMATIC HYSTERESIS LOOP RECORDER Original Filed Sept. 27, 1956 5 Sheets-Sheet 2 Jan. 10, 1961 E. R. czERLlNsKY ET AL 2,968,004

ANALYZER cH ANNEL. FOR USE IN AN AUTOMATIC HYSTERESIS LOOP RECORDER Original Filed Sept. 27, 1956 3 Sheets-Sheet 3 United States Patent ANALYZER CHANNEL FOR USE IN AN AUTO- MATIC HYSTERESIS LOOP RECORDER Ernst R. Czerlinsky, Arlington, and Raymond A. Mac- Millan, Greenwood, Mass., assignors to the United States of America as represented by the Secretary of the Air Force Original application Sept. 27, 1956, Ser. No. 612,569. Divided and this application Aug. 18, 1958, Ser. No. 755,817

1 Claim. (Cl. 328-133) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to us of any royalty thereon.

This is a divisional application of the application of Ernst R. Czerlinsky and Raymond A. MacMillan, tiled September 27, 1956, Serial No. 612,569, Patent No. 2,922,949.

This invention relates to an analyzer channel for use in an automatic hysteresis loop recorder. 1

One object of the invention is to provide an analyzer channel for switching half period segments of magnetizing current, or the voltage induced in the secondary winding of a sample under test over the entire period of the magnetizing current.

This and other objects will be more fully understood from the following detailed description taken with the drawings wherein:

Fig. 1 is a block diagram of the measuring and recordingv device in which the analyzer channel of the invention may be used.

Fig. 2 is a schematic wiring diagram of an analyzer channel in accordance with the present invention.

Fig. 3 is a schematic wiring diagram of a circuit to aid in the explanation of the operation of the analyzer channel of Fig. 2.

Fig. 4 shows waveforms for illustrating the operation of the analyzer channel of Fig. 2.

Referring to Fig. l of the drawing, the device consists generally of a frequency source 11, which may have a frequency range of from 50 to 5000 c.p.s., a circuit 20 for measuring the magnetic tlux induced in a sample 10, a circuit 30 for measuring the magnetizing force, a phase rotator circuit 40 and an X-Y recorder 50.

Frequency source 11 supplies the magnetizing force to the sample by way of winding 12. The voltage Vs induced in the secondary winding 23 is proportional to the derivative of the magnetic ux B induced in the core by the magnetizing force H. The voltage across winding 23 is applied to an analyzer channel 27 through a cathode follower 24, an amplilier 25 and a cathode follower coui pling circuit 26. The switching and stepping of the half period segments are accomplished by the cooperation of the analyzer channel and the phase rotator.

The operation of the analyzer channel 27 and the phase rotator 41 is best explained with reference to Fig. 2 and Fig. 3.

Referring tirst to Fig. 3, tube T11, has its cathode connected directly to the anode of tube T11, and its anode connected to the cathode of T11, through a resistor R1. With no external voltage applied, a certain number of electrons will be emitted from each cathode by thermal emission. Due to the tube connections these electrons will cause a current to circulate between the two tubes and no current will tlow through R2, if the potentiometer 2,968,004 Patented aan. 10, 1961 ICC alternating grid voltage and to cutoff during the negativehalf cycle. Thus either tube T1,1 or T11, is made conducting for one half cycle of grid voltage and both are cut ofr" during the following half cycle. If voltages V, and V1 are obtained from the same power supply the current Ir through R2 is proportional to the voltage V1 duringV vthe conducting times t1-t2, t3-l4, etc. as shown in Fig. 4, c. The current is zero during the times r11-t3, t.1-t5, etc,

The phase difference between V1 and Vg determines the segment of voltage V1 that causes the current to ow in R2 during the time t1`-t2, t3-t4, etc. When the phase difference is zero, the current lr is as shown in Fig. 4,c and will have an average value equal to With the phase dilerence equal to 90.7, the current I1.v

will be as shown in Fig. 4, f and will have an` averageA value equal to zero. With the phase diferenceequal t0 Ir will be as shown in Fig, 4 i and will have an` average value equal to n In.the general case when a voltage containing a funda,- mental and odd harmonics is applied, the average current produced by the fundamental is:

And the average produced by the nth harmonic is:

tx cos met Then if the conducting time t2-t1=T/2 the average currents are:

where er1 represents the phase angle between V1 and Vg.

The phase difference between voltage V1 and Vg can be swept continuously through phase angles of from 0 to 360 by a phase rotator 41. The phase rotator should receive its energizing current from the same frequency supply that supplies V1 and may be driven by adjustable speed motor.

Referring now to Fig. 2 wherein resistor R2 of Fig. 3 is replaced by an L-C circuit, the inductance 28L, the condenser 28C and tubes T1 and T-Z make up an R--L--C circuit, with the distributed R being the sum of resistance of the inductance, resistances of tubes T11, and T11, and connected circuit.

When a sinusoidal voltage of the same frequency as V,z is applied to terminals 44 and 44 with a phase difference between the two voltages equal to zero, the direct (D.C.) voltage at terminals 45 and 45 rises to a value of 3 times the amplitude of the voltage at terminals 44 and 44', if

wLc=1/\l u; w y and if there is no discharge during the cutoff time, w being the frequency for switching tubes T1a and Tn, between full conducting and cutoff. With L=400 h, c=400 pf. and R=l5,000 ohms, condenser 28C will charge to 99% of its nal amount in about 70 seconds.

'If a second set of tubes T2, and T21, are provided having a voltage Vg' applied to their grids which is from the same source as Vg but which is 180 out of phase with respect to Vg, these tubes will conduct during the times that ,tubes T1a and TU, are cut off and the voltage at terminals 45 and 45 rises to a value not greater than times the amplitude of the voltage at terminals 44 and 44'. Since tubes T2, and T21, will conduct during the time that tubes T1, and Tu, are cut off, the energy stored in the choke 28L will, in a large part, be transferred to the condenser 28C, thereby shortening the charging time for the condenser to approximately 4 sec. The final voltage on the condenser then vwill be a D.C. voltage with a negligible superimposed alternating voltage. As can be seen the speed of the phase rotator must be made slow enough to allow the condenser 28C to reach the proper value of charge for each phase position of the phase rotator.

Then if the voltage applied to terminals 44 and 44 is the output of cathode follower 26 and V,z is the output of phase rotator 41, the D C. voltage across terminals 45 and 45 is proportional to the flux B.

As can be seen from Fig. l, this analyzer channel can also be used for obtaining a D.C. voltage proportional to the magnetizing force H.

There is thus provided an analyzer channel for switching half period segments of magnetizing current or the voltage induced in the secondary winding of a sample under test over the entire period of the maguetizing current.

While the invention has been described with reference to a particular embodiment, it will be understood that numerous changes may be made without departing from the general principles and scope of the invention.

We claim:

A switching circuit comprising a first pair of electron discharge tubes, cach tube having an anode, a cathode and a control grid, rst means connecting the anode of one of said tubes to the cathode of the other tube, second means connecting the cathode of said one of said tubes to the anode of said other tube, an alternating voltage supply source, a first circuit comprising an inductance and a capacitance, said first pair of tubes, said voltage source and said first circuit being connected in series, a second 'circuit for applying the alternating voltage from said source to the grids of said first pair of tubes, said second circuit comprising phase rotating means for changing the phase relation between the voltage in said iirst circuit and the voltage applied to the grids of said first pair of tubes, a second pair of electron discharge tubes, each tube having an anode, a cathode and a control grid, third means connecting the anode of one of said second pair of tubesr to the cathode of the other of said second pair of tubes, fourth means connecting the cathode of said one of said second pair of tubes to the anode of said other of said second pair of tubes, said second pair of tubes being connected in parallel with said rst circuit, and tifth means for applying to the grids of said second pair of tubes an alternating voltage which is degrees out of phase with respect to the voltage applied to the grids of said first pair of tubes.

FOREIGN PATENTS Great Britain June 5, 1936 

